Two Not Better Than One for Mammary Artery Grafts?

5-year outcomes similar in ART trial

Doubling up on internal-thoracic-artery grafts for multivessel coronary artery bypass grafting (CABG) didn't improve 5-year outcomes but was associated with additional harms compared with a single internal mammary and vein grafts, the ART trial showed.

The 5-year rate of mortality was similar compared with using a single internal thoracic artery for the procedure (8.7% versus 8.4%, HR 1.04, 95% CI 0.81-1.32), Marcus Flather, MBBS, of the University of East Anglia in Norwich, England, and colleagues found.

The composite rate of death from any cause, MI, or stroke was likewise similar at 12.2% and 12.7%, respectively (HR 0.96, 95% CI 0.79-1.17), they reported online in the New England Journal of Medicine and at a late-breaking clinical trial session at the American Heart Association meeting in New Orleans.

Timothy Gardner, MD, of the Christiana Hospital in Newark, Del., and a past president of the AHA, called the findings surprising.

"However, I am not deterred in my feeling that for younger patients needing multiple grafting that the evidence of improved patency of arterial grafts compared to vein grafts, at least based on historical data, suggests they should still be considered for both mammary artery grafts," he told MedPage Today. "This is going to have an impact on guidelines, because here was a randomized controlled trial that did not show benefit."

And, as anticipated for the more complex procedure, there were some additional risks. Sternal wound complications occurred in 3.5% of patients getting bilateral internal thoracic artery grafts versus 1.9% in the single-graft group (P=0.005); sternal reconstruction was required in 1.9% versus 0.6%, respectively (P=0.002).

Major bleeding was similar between groups in the Arterial Revascularization Trial (ART), which included 3,102 patients at 28 cardiac surgical centers in seven countries who were randomly assigned single or bilateral internal-thoracic-artery grafting.

As to why bilateral hasn't turned out better yet, the researchers noted several factors, including excellent medical therapy in both groups that may be improving outcomes for vein graft patency, variation in surgeon experience, and that "the rate of vein-graft failure within 5 years may not be high enough to have an obvious adverse clinical effect."

"I think we have to be a little careful in interpreting these results. This is an interim analysis at 5 years, and the study was designed with a primary outcome ascertainment at 10 years," Patrick O'Gara, MD, a cardiologist at Brigham and Women's Hospital in Boston, cautioned in an interview. "It may come to pass that with an additional 5 years of follow-up there may be a different signal of efficacy between the strategies. But I don't think the signal of harm will go away because that emerged early and didn't go away."

The trial was supported by grants from the British Heart Foundation, the U.K. Medical Research Council, and the National Institute of Health Research Efficacy and Mechanism Evaluation Program.

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